CN113346126A - Composite solid electrolyte, all-solid-state lithium ion battery and preparation method thereof - Google Patents
Composite solid electrolyte, all-solid-state lithium ion battery and preparation method thereof Download PDFInfo
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Abstract
The application discloses compound solid electrolyte, including bilayer polymer electrolyte and cladding in inorganic solid electrolyte in the bilayer polymer electrolyte, bilayer polymer electrolyte includes porous carbon fiber layer and in situ polymerization layer, porous carbon fiber layer includes three-dimensional cross-linked carbon fiber electrolyte, in situ polymerization layer include the normal position grow in the in situ polymer electrolyte of carbon fiber electrolyte surface, in situ polymer electrolyte fills in the pore that the three-dimensional cross-linking of carbon fiber electrolyte formed, inorganic solid electrolyte cladding in the carbon fiber electrolyte. The inorganic solid electrolyte is creatively coated by the double-layer polymer electrolyte, so that the composite solid electrolyte has excellent conductivity and higher mechanical stability.
Description
Technical Field
The invention relates to the field of lithium ion batteries, in particular to a composite solid electrolyte, an all-solid-state lithium ion battery and a preparation method thereof.
Background
Lithium ion batteries have been widely used in the automotive field and in digital consumer electronics due to their light weight, high energy density, and the like. Generally, a lithium ion battery consists of four parts: the electrolyte is an important component and plays roles of ion conduction and electronic insulation. The conventional lithium ion battery uses liquid organic electrolyte, which is easy to cause some safety problems, such as easy volatilization, easy flammability and explosion, gas generation, easy side reaction and the like. Solid-state batteries, in turn, typically use solid-state electrolytes in the oxide, sulfide or polymer systems. The battery does not contain liquid electrolyte, so that the safety can be greatly improved, in addition, the battery uses solid electrolyte, lithium metal with high energy density can be adopted as a negative electrode, and further, the energy density of the battery can be improved.
The inorganic solid electrolyte comprises an inorganic oxide system and an inorganic sulfide system, wherein the inorganic oxide system has relatively loose manufacturing conditions, low conductivity and high density, and the inorganic sulfide system has high conductivity and is very sensitive to moisture and can generate toxic gaseous hydrogen sulfide when meeting water. Compared with inorganic solid electrolytes, polymer solid electrolytes are more suitable for large-scale production, but at present, the conventional polymer solid electrolytes also have the problems of narrow temperature use range and relatively poor mechanical support and interface stability, so that the practical application of the polymer solid electrolytes is greatly limited. The composite solid electrolyte can combine the advantages of inorganic electrolyte and polymer electrolyte, has better application prospect, and how to obtain the composite solid electrolyte with high ionic conductivity and high interface stability is still the difficulty of realizing the application of the composite solid electrolyte.
Disclosure of Invention
The application aims to provide a composite solid electrolyte, an all-solid-state lithium ion battery and a preparation method thereof.
In order to achieve the purpose, the following technical scheme is adopted in the application:
the application discloses in a first aspect, composite solid electrolyte, including bilayer polymer electrolyte and inorganic solid electrolyte of cladding in bilayer polymer electrolyte, bilayer polymer electrolyte includes porous carbon fiber layer and in situ polymerization layer, porous carbon fiber layer includes three-dimensional crosslinked carbon fiber electrolyte and the inorganic solid electrolyte of cladding in carbon fiber electrolyte, in situ polymerization layer includes the in situ polymer electrolyte of in situ growth in carbon fiber electrolyte surface, in situ polymer electrolyte fills in the pore that carbon fiber electrolyte three-dimensional crosslinking formed.
It is worth explaining that, the inorganic solid electrolyte is creatively coated by the double-layer polymer electrolyte, on one hand, the inorganic solid electrolyte is prevented from reacting with water by the coating effect of the carbon fiber electrolyte in the porous carbon fiber layer, the stability of the inorganic solid electrolyte is ensured, and the composite solid electrolyte has excellent and stable conductivity; on the other hand, the in-situ polymer electrolyte in the in-situ polymerization layer is coated on the carbon fiber electrolyte and filled in the pores formed by three-dimensional crosslinking of the carbon fiber electrolyte in a mode of in-situ chemical growth on the surface of the carbon fiber electrolyte, so that the porous carbon fiber layer has better mechanical stability, a more stable interface is provided between a positive electrode material and a negative electrode material, the contact between the solid electrolyte and the interfaces of the positive electrode and the negative electrode is improved, and the interface impedance is reduced; in addition, the double-layer polymer electrolytic coating structure can also effectively inhibit the growth of lithium dendrites, and greatly improves the safety performance of the battery.
In one implementation of the present application, the inorganic solid state electrolyte includes at least one of a solid sulfide electrolyte or a solid oxide electrolyte;
the solid sulfide electrolyte includes Li10GeP2S12；
The solid oxide electrolyte comprises Li7La3Zr2O12Or Li doped with Ga or Ta7La3Zr2O12；
Preferably, the porous carbon fiber layer contains a lithium salt;
preferably, the lithium salt comprises at least one of lithium bistrifluoromethanesulfonimide (LiTFSI), lithium nitrate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate;
preferably, the in situ polymerized layer further comprises an initiator;
preferably, the initiator comprises lithium hexafluorophosphate;
preferably, the carbon fiber electrolyte is obtained by electrospinning a polymer precursor;
preferably, the polymer precursor comprises at least one of polymethyl methacrylate, polyacrylonitrile and polyethylene oxide;
preferably, the in-situ polymer electrolyte is obtained by in-situ polymerization of polymer monomers;
preferably, the polymeric monomer is 1, 3-dioxolane.
A second aspect of the present application discloses a method for preparing a composite solid electrolyte, comprising:
adding an inorganic solid electrolyte, a lithium salt and a polymer precursor into a first organic solvent according to a certain proportion, stirring to obtain a first solution, carrying out electrostatic spinning on the first solution to obtain a three-dimensional crosslinked carbon fiber electrolyte coated with the inorganic solid electrolyte and the lithium salt, and carrying out tabletting and slicing on the carbon fiber electrolyte to obtain a porous carbon fiber layer;
preparing a polymer monomer precursor solution, placing the polymer monomer precursor solution in pores of the porous carbon fiber layer, and forming an in-situ polymer electrolyte through in-situ polymerization to obtain the composite solid electrolyte.
In one implementation of the present application, the polymer precursor includes at least one of polymethyl methacrylate, polyacrylonitrile, and polyethylene oxide;
preferably, the inorganic solid electrolyte: lithium salt: the polymer precursor =1:2: 2-2: 2: 1;
preferably, the first organic solvent comprises at least one of ethanol, N-dimethylformamide, and acetone;
preferably, the mass fraction of the first solution is 20-30%;
preferably, the parameters of electrospinning are: the spinning temperature is 25-45 ℃, the spraying speed is 0.05-0.1 ml/min, the voltage is 18-28 Kv, and the distance between the positive pole and the negative pole is 12-28 cm.
In one implementation of the present application, the inorganic solid electrolyte is prepared according to the following method:
ball-milling and calcining the sulfide in a reducing atmosphere, and then cooling to room temperature to obtain an inorganic solid electrolyte;
preferably, the sulfide includes Li2S，P2S5And GeS2The inorganic solid electrolyte comprises Li10GeP2S12；
Preferably, the ball milling time is 30-50h, the calcining temperature is 400-.
In one implementation of the present application, preparing a polymer monomer precursor solution includes:
uniformly mixing an initiator and a polymer monomer to prepare a polymer monomer precursor solution;
preferably, the volume fraction of the polymer monomer is 25% to 100%;
preferably, the uniformly mixing the initiator and the polymer monomer specifically comprises:
adding an initiator into a second organic solvent, stirring and dissolving to obtain a second solution, adding a polymer monomer into the second solution, and uniformly mixing;
preferably, the initiator comprises lithium hexafluorophosphate;
preferably, the concentration of the initiator in the second solution is 1-3 mol/L;
preferably, the second organic solvent comprises at least one of ethylene carbonate, diethyl carbonate, dimethyl carbonate and propylene carbonate;
preferably, the polymeric monomer comprises a 1, 3-dioxolane monomer.
In a third aspect of the present application, a composite solid electrolyte prepared by the above preparation method is disclosed.
A fourth aspect of the present application discloses an application employing the above composite solid electrolyte.
A fifth aspect of the present application discloses an all solid-state lithium ion battery employing the above composite solid electrolyte.
The sixth aspect of the present application discloses a preparation method of the above all-solid-state lithium ion battery, including the steps of:
assembling a battery from bottom to top or from top to bottom according to the sequence of a negative electrode shell, a gasket, a negative electrode plate, a porous carbon fiber layer, a positive electrode plate and a positive electrode shell;
and adding the polymer monomer precursor solution into the assembled battery, sealing, and standing to obtain the all-solid-state lithium ion battery.
Due to the adoption of the technical scheme, the beneficial effects of the application are as follows:
the inorganic solid electrolyte is creatively coated by the double-layer polymer electrolyte, so that on one hand, the inorganic solid electrolyte is prevented from reacting with water by the coating effect of the carbon fiber electrolyte in the porous carbon fiber layer, the stability of the inorganic solid electrolyte is ensured, and the composite solid electrolyte has excellent conductivity; on the other hand, the in-situ polymer electrolyte in the in-situ polymerization layer is coated on the carbon fiber electrolyte and filled in the pores formed by three-dimensional crosslinking of the carbon fiber electrolyte in a mode of in-situ chemical growth on the surface of the carbon fiber electrolyte, so that the porous carbon fiber layer has better mechanical stability, a more stable interface is provided between a positive electrode material and a negative electrode material, the contact between the solid electrolyte and the interfaces of the positive electrode and the negative electrode is improved, and the interface impedance is reduced; in addition, the double-layer polymer electrolytic coating structure can also effectively inhibit the growth of lithium dendrites, and greatly improves the safety performance of the battery.
Drawings
Fig. 1 is a schematic structural diagram of an all-solid-state lithium ion battery provided in example 1 and example 2;
fig. 2 is a long cycle test chart of the all-solid-state lithium ion battery provided in example 2;
fig. 3 is a scanning electron micrograph of the composite solid electrolyte provided in example 3.
Detailed Description
The present invention will be described in further detail with reference to the following embodiments. In the following description, numerous details are set forth in order to provide a better understanding of the present application. However, those skilled in the art will readily recognize that some of the features may be omitted in different instances or may be replaced by other materials, methods. In some instances, certain operations related to the present application have not been shown or described in detail in order to avoid obscuring the core of the present application from excessive description, and it is not necessary for those skilled in the art to describe these operations in detail, so that they may be fully understood from the description in the specification and the general knowledge in the art.
Furthermore, the features, operations, or characteristics described in the specification may be combined in any suitable manner to form various embodiments. Also, the various steps or actions in the method descriptions may be transposed or transposed in order, as will be apparent to one of ordinary skill in the art. Thus, the various sequences in the specification are for the purpose of clearly describing one embodiment only and are not meant to be necessarily order unless otherwise indicated where a certain order must be followed.
In the description of the present application, "at least one" means one or more, "a plurality" means two or more. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, "at least one (one) of a, b, or c," or "at least one (one) of a, b, and c," may each represent: a, b, c, a-b (i.e. a and b), a-c, b-c or a-b-c, wherein a, b and c can be single or multiple respectively.
It should be understood that the weight of the related components mentioned in the embodiments of the present application may not only refer to the specific content of each component, but also represent the proportional relationship of the weight among the components, and therefore, it is within the scope of the disclosure that the content of the related components is scaled up or down according to the embodiments of the present invention. Specifically, the weight in the examples of the present application may be in units of mass known in the chemical industry, such as μ g, mg, g, and kg.
All the starting materials of this example, the sources of which are not particularly limited, are either commercially available or prepared according to conventional methods well known to those skilled in the art.
All the raw materials in this example are not particularly limited in purity, and the raw materials in this example preferably have purity which is conventional in the field of analytical purification or sodium ion battery materials.
In order to solve the problem that the conventional solid electrolyte still has low conductivity or poor stability, the embodiment provides a composite solid electrolyte, which includes a double-layer polymer electrolyte and an inorganic solid electrolyte coated in the double-layer polymer electrolyte, wherein the double-layer polymer electrolyte includes a porous carbon fiber layer and an in-situ polymerization layer, the porous carbon fiber layer includes a three-dimensionally crosslinked carbon fiber electrolyte and an inorganic solid electrolyte coated in the carbon fiber electrolyte, the in-situ polymerization layer includes an in-situ polymer electrolyte in-situ grown on the surface of the carbon fiber electrolyte, and the in-situ polymer electrolyte is filled in pores formed by three-dimensionally crosslinking the carbon fiber electrolyte. It is worth explaining that, the inorganic solid electrolyte is creatively coated by the double-layer polymer electrolyte, on one hand, the inorganic solid electrolyte is prevented from reacting with water by the coating effect of the carbon fiber electrolyte in the porous carbon fiber layer, the stability of the inorganic solid electrolyte is ensured, and the composite solid electrolyte has excellent conductivity; on the other hand, the in-situ polymer electrolyte in the in-situ polymerization layer is coated on the carbon fiber electrolyte and filled in the pores formed by three-dimensional crosslinking of the carbon fiber electrolyte in a mode of in-situ chemical growth on the surface of the carbon fiber electrolyte, so that the porous carbon fiber layer has better mechanical stability, a more stable interface can be provided between a positive electrode material and a negative electrode material, the contact between the solid electrolyte and the interfaces of the positive electrode and the negative electrode is improved, and the interface impedance is reduced; in addition, the double-layer polymer electrolytic coating structure can also effectively inhibit the growth of lithium dendrites, and greatly improves the safety performance of the battery.
In this embodiment, the components of the inorganic solid electrolyte are not particularly limited as long as they can participate in electrostatic spinning to coat the carbon fiber electrolyte and improve the conductivity of the double-layer polymer electrolyte. In particular, the inorganic solid electrolyte may be a solid sulfide, for example, Li10GeP2S12For increasing the ionic conductivity of the composite solid electrolyte, or solid oxides, e.g. Li7La3Zr2O12Or Li doped with Ga or Ta7La3Zr2O12Or alternatively a thiogermorite-type compound Li6PS5X（X=F,Cl,Br,I）。
In one implementation of this embodiment, in order to improve the lithium ion conductivity of the porous carbon fiber layer, the porous carbon fiber layer contains a lithium salt, and the lithium salt includes at least one of lithium bis (trifluoromethanesulfonylimide) (LiTFSI), lithium nitrate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, and lithium hexafluoroarsenate, and is present as an electrolyte component for improving the lithium ion conductivity of the porous carbon fiber layer and reducing the internal resistance of the composite solid electrolyte layer.
In an implementation manner of this embodiment, the in-situ polymerization layer further includes an initiator for regulating and controlling a crosslinking polymerization speed and a polymerization degree of the polymer monomer, and specifically, the initiator may be lithium hexafluorophosphate.
In one implementation of this embodiment, the carbon fiber electrolyte is obtained by electrospinning a polymer precursor, and exists in the form of a carbon fiber skeleton, and the carbon fiber electrolyte is internally coated with an inorganic solid electrolyte and a lithium salt.
In one implementation manner of this embodiment, the polymer precursor includes at least one of polymethyl methacrylate, polyacrylonitrile, and polyethylene oxide, and the polymer precursor is jet-spun under the action of a strong electric field to form polymer filaments with nanometer-scale diameters and three-dimensional cross-linked, so as to obtain a three-dimensional cross-linked carbon fiber electrolyte, and three-dimensional pores are formed between the carbon fiber electrolytes.
In an implementation manner of this embodiment, the in-situ polymer electrolyte is obtained by in-situ polymerization of a polymer monomer, where the in-situ polymerization refers to that the polymer monomer is located in a pore formed by three-dimensional cross-linking of the carbon fiber electrolyte, and the polymer electrolyte is formed by "in-situ growth" on the surface of the carbon fiber electrolyte, so as to fill the three-dimensional pore of the porous carbon fiber layer, so that the porous carbon fiber layer has better mechanical stability, and can provide a more stable interface between the positive electrode material and the negative electrode material, improve the interface contact between the solid electrolyte and the positive electrode and the negative electrode, and reduce the interface impedance; in a specific implementation of this example, the polymer monomer is 1, 3-dioxolane.
Therefore, the present embodiment also provides a method for preparing a composite solid electrolyte, including the following steps:
s201: adding an inorganic solid electrolyte, a lithium salt and a polymer precursor into a first organic solvent according to a certain proportion, stirring to obtain a first solution, carrying out electrostatic spinning on the first solution to obtain a three-dimensional crosslinked carbon fiber electrolyte coated with the inorganic solid electrolyte and the lithium salt, and carrying out tabletting and slicing on the carbon fiber electrolyte to obtain a porous carbon fiber layer;
specifically, in order to make the porous carbon fiber electrolyte have high conductivity, an inorganic solid electrolyte: lithium salt: dissolving a polymer precursor into an organic solvent according to the proportion of 1:2: 2-2: 2:1, and fully stirring for 6-10h to obtain a first solution, wherein the polymer precursor comprises at least one of polymethyl methacrylate, polyacrylonitrile and polyethylene oxide, the first organic solvent comprises at least one of ethanol, N, N-dimethylformamide and acetone, and the mass fraction of the first solution is 20% -30%; the parameters for electrospinning the first solution were: the spinning temperature is 25-45 ℃, the spraying speed is 0.05-0.1 ml/min, the voltage is 18-28 Kv, and the distance between the positive electrode and the negative electrode is 12-28 cm, so that a three-dimensional fiber cluster formed by three-dimensionally crosslinking the carbon fiber electrolyte with uniform thickness, namely a porous carbon fiber layer, is obtained.
S202: preparing a polymer monomer precursor solution, placing the polymer monomer precursor solution in pores of the porous carbon fiber layer, and forming an in-situ polymer electrolyte through in-situ polymerization to obtain a composite solid electrolyte;
specifically, the polymer monomer precursor solution is used for filling pores formed by three-dimensional crosslinking of a carbon fiber electrolyte, and an in-situ polymer electrolyte is formed through polymerization reaction under the action of an initiator, the in-situ polymer electrolyte fills and coats the carbon fiber electrolyte, and an inorganic solid electrolyte and a lithium salt are coated in the carbon fiber electrolyte, so that the composite solid electrolyte with a double-layer polymer electrolyte coating structure is obtained.
In one implementation of this embodiment, the inorganic solid electrolyte is prepared by the following method:
and carrying out ball milling and calcination on the sulfide or the metal oxide in a reducing atmosphere, and then cooling to room temperature to obtain the inorganic solid electrolyte.
In particular, the inorganic solid electrolyte may be a solid sulfide, for example, Li10GeP2S12(ii) a In particular, the sulfide is represented by Li2S，P2S5，GeS2When used as a raw material, an inorganic solid electrolyte Li can be obtained10GeP2S12To increase the conductivity of the inorganic solid electrolyte. In one implementation of this example, an inorganic solid electrolyte, Li, was prepared10GeP2S12When in use, the ball milling time of the sulfide is 30-50h, the calcining temperature is 400-500 ℃, and the calcining time is 6-10 h. In an implementation manner of this embodiment, the preparing the polymer monomer precursor solution specifically includes:
and uniformly mixing an initiator and a polymer monomer to prepare the polymer monomer precursor solution.
Specifically, the initiator can be lithium hexafluorophosphate and is used for regulating and controlling the polymerization rate and the polymerization degree of the polymer monomer in the pores of the porous carbon fiber layer, the polymer monomer can be a 1, 3-dioxolane monomer and can be continuously subjected to ring-opening polymerization under the action of the initiator, a polymer is formed in situ in the pores between the surface of the carbon fiber and the carbon fiber, the transition of the polymer monomer from a liquid state to a solid state is realized, and thus the composite solid electrolyte with a double-layer polymer coating structure is formed.
In one implementation of this example, to achieve sufficient wetting and initiation of the polymer monomer, a polymer monomer precursor solution was prepared in the following manner: adding an initiator into a second organic solvent, stirring and dissolving to obtain a second solution, adding a polymer monomer into the second solution, and uniformly mixing to obtain a polymer monomer precursor solution, wherein the volume fraction of the polymer monomer in the polymer monomer precursor solution is 25-100%, and the concentration of the initiator in the second solution is 1-3mol/L, so that the polymer monomer is fully initiated, in-situ polymerization forms a polymer electrolyte and fills up pores of the porous carbon fiber layer, and the polymer monomer is converted from a liquid state to a solid state, so that the porous carbon fiber layer is supported, the mechanical stability of the porous carbon fiber layer is effectively improved, and the mechanical stability of the composite solid electrolyte is improved.
In some embodiments, the second organic solvent is a conventional liquid electrolyte solvent, and includes at least one of ethylene carbonate, diethyl carbonate, dimethyl carbonate, and propylene carbonate, for increasing the solubility of the initiator in the second solvent, so that the addition of the polymer monomer to the second solvent can achieve sufficient initiation of the polymer monomer, and the polymer electrolyte formed by in-situ polymerization of the polymer monomer can be uniformly dispersed and filled in the pores of the porous carbon fiber layer.
Therefore, the present embodiment also provides a composite solid electrolyte prepared by the above preparation method, so as to obtain a composite solid electrolyte having a double-layer polymer electrolyte coated inorganic solid electrolyte, which has not only excellent conductivity, but also excellent mechanical stability.
The embodiment also provides an application of the composite solid electrolyte, for example, an application of the composite solid electrolyte in an all-solid-state lithium ion battery, so that the conductivity of lithium ions is improved, a more stable interface is provided between the anode material and the cathode material in the charge and discharge cycle process of the solid battery, the interface contact between the solid electrolyte and the anode and the cathode is improved, and the interface impedance is reduced.
Therefore, the present embodiment also provides an all solid-state lithium ion battery using the above composite solid electrolyte.
Further, the embodiment also provides a preparation method of the all-solid-state lithium ion battery, which includes the following steps:
assembling a battery from bottom to top or from top to bottom according to the sequence of a negative electrode shell, a gasket, a negative electrode plate, a porous carbon fiber layer, a positive electrode plate and a positive electrode shell;
and adding the polymer monomer precursor solution into the assembled battery, sealing, and standing to obtain the all-solid-state lithium ion battery.
Specifically, a first porous carbon fiber layer containing a solid sulfide electrolyte is placed into a battery, and is sequentially assembled with a positive electrode and a negative electrode without sealing the battery, then a prepared 1, 3-dioxolane monomer containing an initiator is injected into the porous carbon fiber layer, the battery is sealed, the battery is kept stand for a period of time, and after the polymer monomer is continuously subjected to ring-opening polymerization and grows in situ in pores formed by three-dimensional crosslinking of the carbon fiber surface and the carbon fiber, the conversion from liquid to solid is realized, and the all-solid-state lithium ion battery can be obtained.
This application will be further illustrated by the following specific examples. It should be understood that the examples are illustrative only and are not to be construed as limiting the scope of the present application.
Example 1
Mixing Li2S，P2S5，GeS2And the raw materials are mixed according to the weight ratio of 5: 1:1, and ball milling for 40 hours under the argon condition. Then calcining the mixture for 8 hours at the temperature of 400 ℃ in an argon environment, and cooling the calcined mixture to room temperature to obtain Li10GeP2S12. Weighing a certain mass of Li10GeP2S12The preparation method comprises the following steps of dissolving lithium bis (trifluoromethanesulfonyl) imide and polyacrylonitrile =2:2:1 in N, N-dimethylformamide together, stirring the prepared solution for 6 hours at room temperature to uniformly mix the solution, wherein the mass fraction of the prepared solution is 20%. Putting the stirred uniform solution into an injector, and then carrying out electrostatic spinning, wherein the operation parameters are as follows: the spinning temperature is 25 ℃, and the spraying speed is 0.05 ml min-1The voltage is 18 Kv, and the distance between the positive electrode and the negative electrode is 15 cm. And further tabletting the carbon fiber electrolyte subjected to electrostatic spinning, slicing and drying to obtain a porous carbon fiber layer for storage and standby.
The following operations were carried out in a glove box, adding to ethylene carbonate: stirring and dissolving diethyl carbonate =1:1 mixed solvent to obtain a solution with the concentration of 1.3mol/L, adding 1, 3-dioxolane monomer into the solution, wherein the volume fraction of the 1, 3-dioxolane monomer is 30%, and uniformly mixing. In the drying box, the negative electrode uses a lithium sheet, and the positive electrode main material uses commercial lithium iron phosphate, and as shown in fig. 1, the lithium sheet 3, the porous carbon fiber layer 4, the positive electrode sheet 5 and the positive electrode shell 6 are placed in the manner of a negative electrode shell 1, a gasket 2 and a positive electrode shell 6. The assembled cell was then charged with a polymer monomer precursor solution with 1, 3-dioxolane monomer and lithium hexafluorophosphate using a syringe. And sealing the battery and standing for 2 days to obtain the all-solid-state lithium ion battery. As shown in fig. 2, fig. 2 shows cycle data of the all-solid-state lithium ion battery at a current of 0.5C, and it can be seen from the figure that after 500 cycles, the all-solid-state lithium ion battery of the present example maintains a capacity of 95% or more, and exhibits very excellent cycle stability.
Example 2:
mixing Li2S，P2S5，GeS2And the raw materials are mixed according to the weight ratio of 5: 1:1, and ball milling for 35 hours under the argon condition. Then calcining the mixture for 8 hours at 500 ℃ in an argon environment, and cooling the calcined mixture to room temperature to obtain Li10GeP2S12. Weighing a certain mass of Li10GeP2S12The preparation method comprises the following steps of dissolving lithium bis (trifluoromethanesulfonyl) imide and polyacrylonitrile =1:2:2 in N, N-dimethylformamide together, stirring the prepared solution for 6 hours at room temperature to uniformly mix the solution, wherein the mass fraction of the prepared solution is 30%. Putting the stirred uniform solution into an injector, and then carrying out electrostatic spinning, wherein the operation parameters are as follows: the spinning temperature is 45 ℃, and the spraying speed is 0.1 ml min-1The voltage is 26 Kv, and the distance between the positive electrode and the negative electrode is 25 cm. And further tabletting the carbon fiber electrolyte subjected to electrostatic spinning, slicing and drying to obtain a porous carbon fiber layer for storage and standby.
The following operations are performed in the glove box: addition to ethylene carbonate: stirring and dissolving diethyl carbonate =1:1 mixed solvent to obtain solution with the concentration of 2.8mol/L, adding 1, 3-dioxolane monomer with the volume fraction of 30% into the solution, and uniformly mixing. In the dry box, the negative electrode uses a lithium sheet and the positive electrode uses a nickel cobalt manganese ternary positive electrode material, such as the commercial positive electrode material ternary NCM 523. As shown in fig. 1, the negative electrode case 1, the gasket 2, the lithium sheet 3, the porous carbon fiber layer 4, the positive electrode sheet 5, and the positive electrode case 6 are placed. The assembled cell was then charged with a polymer monomer precursor solution with 1, 3-dioxolane monomer and lithium hexafluorophosphate using a syringe. And sealing the battery and standing for 6 days to obtain the all-solid-state lithium ion battery.
Example 3
Mixing Li2S，P2S5，GeS2And the raw materials are mixed according to the weight ratio of 5: 1:1, and ball milling for 50 hours under the argon condition. Then calcining for 8h at 450 ℃ in an argon environment, and cooling to room temperature to obtain Li10GeP2S12. Weighing a certain mass of Li10GeP2S12The preparation method comprises the following steps of dissolving lithium bis (trifluoromethanesulfonyl) imide and polyacrylonitrile =1.5:1.5:2 in N, N-dimethylformamide together, stirring the prepared solution for 6 hours at room temperature to uniformly mix the solution, wherein the mass fraction of the prepared solution is 25%. Putting the stirred uniform solution into an injector, and then carrying out electrostatic spinning, wherein the operation parameters are as follows: the spinning temperature is 35 ℃, and the spraying speed is 0.8 ml min-1The voltage is 22 Kv, and the distance between the positive electrode and the negative electrode is 20 cm. And further tabletting the carbon fiber electrolyte subjected to electrostatic spinning, slicing and drying to obtain a porous carbon fiber layer, and storing for later use.
The following operations are performed in the glove box: addition to ethylene carbonate: diethyl carbonate: stirring and dissolving in a mixed solvent of dimethyl carbonate =1:1:1, adding 1, 3-dioxolane monomer with volume fraction of 45% into the solution to obtain a solution with concentration of 2mol/L, and uniformly mixing. And (3) taking the single porous carbon fiber layer, dropwise adding the polymer monomer precursor solution with the 1, 3-dioxolane monomer and the lithium hexafluorophosphate on two sides of the porous carbon fiber layer by using a needle tube, and standing for 4 days to obtain the composite solid electrolyte with the double-layer coating structure. As shown in FIG. 3, FIG. 3 is a scanning electron microscope image of the composite solid electrolyte, it can be seen that the polymer monomer can be well wrapped on the surface of the carbon fiber after polymerization, and tests show that the composite solid electrolyte can be used at a temperature of 25 DEG CThe ionic conductivity of the material can reach 6.1 multiplied by 10-4 S cm-1。
The present application has been described with reference to specific examples, which are provided only to aid understanding of the present invention and are not intended to limit the present invention. For a person skilled in the art to which the invention pertains, several simple deductions, modifications or substitutions may be made according to the idea of the invention.
Claims (10)
1. The composite solid electrolyte is characterized by comprising a double-layer polymer electrolyte and an inorganic solid electrolyte coated in the double-layer polymer electrolyte, wherein the double-layer polymer electrolyte comprises a porous carbon fiber layer and an in-situ polymerization layer, the porous carbon fiber layer comprises a three-dimensionally crosslinked carbon fiber electrolyte, the in-situ polymerization layer comprises an in-situ polymer electrolyte in situ grown on the surface of the carbon fiber electrolyte, the in-situ polymer electrolyte is filled in pores formed by three-dimensionally crosslinking the carbon fiber electrolyte, and the inorganic solid electrolyte is coated in the carbon fiber electrolyte.
2. The composite solid-state electrolyte of claim 1, wherein the inorganic solid-state electrolyte comprises at least one of a solid sulfide electrolyte or a solid oxide electrolyte;
the solid sulfide electrolyte includes Li10GeP2S12；
The solid oxide electrolyte comprises Li7La3Zr2O12Or Li doped with Ga or Ta7La3Zr2O12；
The porous carbon fiber layer contains a lithium salt;
the lithium salt comprises at least one of lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), lithium nitrate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate and lithium hexafluoroarsenate;
the in-situ polymerized layer further comprises an initiator;
the initiator comprises lithium hexafluorophosphate;
the carbon fiber electrolyte is obtained by electrostatic spinning of a polymer precursor;
the polymer precursor comprises at least one of polymethyl methacrylate, polyacrylonitrile and polyethylene oxide;
the in-situ polymer electrolyte is obtained by in-situ polymerization of polymer monomers;
the polymer monomer is 1, 3-dioxolane.
3. A method of preparing a composite solid electrolyte, comprising:
dissolving an inorganic solid electrolyte, a lithium salt and a polymer precursor in a first organic solvent according to a certain proportion, stirring to obtain a first solution, carrying out electrostatic spinning on the first solution to obtain a three-dimensional crosslinked carbon fiber electrolyte coated with the inorganic solid electrolyte and the lithium salt, and carrying out tabletting and slicing on the carbon fiber electrolyte to obtain a porous carbon fiber layer;
preparing a polymer monomer precursor solution, placing the polymer monomer precursor solution in pores of the porous carbon fiber layer, and carrying out in-situ polymerization to form an in-situ polymer electrolyte so as to obtain the composite solid electrolyte.
4. The production method according to claim 3, wherein the polymer precursor includes at least one of polymethyl methacrylate, polyacrylonitrile, polyethylene oxide;
the inorganic solid electrolyte: lithium salt: the polymer precursor =1:2: 2-2: 2: 1;
the first organic solvent comprises at least one of ethanol, N, N-dimethylformamide and acetone;
the mass fraction of the first solution is 20-30%;
the electrostatic spinning parameters are as follows: the spinning temperature is 25-45 ℃, the spraying speed is 0.05-0.1 ml/min, the voltage is 18-28 Kv, and the distance between the positive pole and the negative pole is 12-28 cm.
5. The production method according to claim 3, wherein the inorganic solid electrolyte is produced by:
ball-milling and calcining the sulfide in a reducing atmosphere, and then cooling to room temperature to obtain an inorganic solid electrolyte;
the sulfide comprising Li2S，P2S5And GeS2The inorganic solid electrolyte comprises Li10GeP2S12；
The ball milling time is 30-50h, the calcining temperature is 400-500 ℃, and the calcining time is 6-10 h.
6. The method according to claim 3, wherein the preparing the polymer monomer precursor liquid specifically comprises:
uniformly mixing an initiator and a polymer monomer to prepare a polymer monomer precursor solution;
the volume fraction of the polymer monomer is 25-100%;
the step of uniformly mixing the initiator and the polymer monomer specifically comprises the following steps:
adding an initiator into a second organic solvent, stirring and dissolving to obtain a second solution, adding a polymer monomer into the second solution, and uniformly mixing;
the initiator comprises lithium hexafluorophosphate;
the concentration of the initiator in the second solution is 1-3 mol/L;
the second organic solvent comprises at least one of ethylene carbonate, diethyl carbonate, dimethyl carbonate and propylene carbonate;
the polymer monomer includes a 1, 3-dioxolane monomer.
7. A composite solid electrolyte prepared by the production method according to any one of claims 3 to 5.
8. Use of a composite solid electrolyte according to claim 1 or 2 or 7.
9. An all-solid lithium ion battery using the composite solid electrolyte of claim 1, 2 or 7.
10. A method of making the all solid-state lithium ion battery of claim 9, comprising the steps of:
assembling a battery from bottom to top or from top to bottom according to the sequence of a negative electrode shell, a gasket, a negative electrode plate, a porous carbon fiber layer, a positive electrode plate and a positive electrode shell;
and adding the polymer monomer precursor solution into the assembled battery, sealing, and standing to obtain the all-solid-state lithium ion battery.
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